In motorcycles, the brake and clutch are manually actuated by means of a lever device that is mounted on the handlebar of the motorcycle, a hydraulic tube extending therefrom to the system to be controlled, such as a hydraulically actuated brake or a clutch.
The lever of the lever device is usually arranged on the grip of the handlebar and the motorcyclist, in order to actuate the lever, grips the handlebar together with the lever and clenches the hand such as to rotate the lever towards the grip. The movement of the lever produces a thrust force acting on the hydraulic piston, the stroke or position thereof defining the amount of fluid pressure inside said hydraulic pipe for controlling the brake or clutch.
Since these levers are the outermost and most exposed part of the motorcycle, the end of the lever can more or less awkwardly hit the ground upon falling, thereby causing the breakage or deformation either of the lever or its support as well as the handlebar-fixing structure.
A broken lever makes a clutch or a manual brake unserviceable, and is accordingly a serious damage that prevents the motorcyclist from continuing a ride or a race.
In order to overcome the problem of accidental failure of the control lever, there has been proposed, for example in the patent U.S. Pat. No. 6,739,133 B1, a lever device provided with a support structure, a transmission portion and a lever being pivotally connected thereto. The transmission portion is always in contact with the hydraulic piston and can be rotated between two extreme angular positions defining an angular actuation stroke therebetween. The first extreme angular position is defined by the abutment of a stop surface of the transmission portion against a corresponding stop surface of the support structure and corresponds to a rest position both for the hydraulic piston and the lever. The second extreme angular position of the transmission portion corresponds to a more or less forward actuation position of the hydraulic piston, based on the force being applied on the lever and transmitted to the transmission portion therefrom.
The lever is pivotally connected to the transmission portion or, alternatively, the lever and transmission portion are connected to each other and the support structure by means of an individual pin allowing them to rotate relative to each other.
The rotation of the lever relative to the transmission portion is restricted in a first direction of rotation due to a lever stop surface abutting against a corresponding stop surface of the transmission portion, such that the lever can rotate the transmission portion in order to advance the hydraulic piston, and thereby actuating the brake or clutch. In the opposite direction to the actuation of the brake or clutch, the lever is freely rotatable such that the same may collapse without breaking in the event of impact. A torsion spring holds the lever elastically in the rest position against the transmission portion in order to prevent that the lever may swing in an uncontrolled manner. A device of this type is depicted in FIG. 1.
This solution, though reducing a lot the risk of failure of the lever, has a disadvantage in that impacts, particularly those transversal to the rotational plane of the lever, are directly (and in an amplified manner, due to the effect of the lever) transmitted to the transmission portion, thereby causing the deformation or breakage of this transmission portion and, at worst, damaging the hydraulic piston against which the transmission portion abuts. Besides seriously impairing the use of the motorcycle after a fall, these damages require subsequent costly servicing if not the replacement of the whole lever device.
The object of the present invention is therefore to improve the control lever device of the prior art such as to further diminish possible damages to the transmission portion and the hydraulic piston due to the impacts against the lever.